1. Field of the Invention
The present invention relates to a coated member on which a coating film is formed on a surface of substrate in order to give it characteristics, such as wear resistance. In particular, it relates to an amorphous-carbon coated member whose coating film comprises an amorphous carbon film.
2. Description of the Related Art
Carbon is an extremely good material in view of resource issues and environmental issues, because its deposits are substantially infinite and it is harmless. As for carbon materials, many materials having various crystalline structures, such as diamonds, diamond-like carbon, graphite, fullerenes, carbon nano-tubes, have been known depending on the bonding forms between atoms. Among them, diamond-like carbon (or amorphous carbon) having an amorphous structure is an attractive functional material which is good in terms of mechanical characteristics, such as wear resistance and solid lubricating property, and which has insulative property, visible/infrared light transmissivity, low dielectric constant, oxygen barrier property, and the like. The amorphous carbon is expected to be applicable to many industrial fields.
Amorphous carbons having various compositions have been studied so far in order to improve the characteristics of amorphous carbon. For example, Japanese Unexamined Patent Publication (KOKAI) No. 6-101,047 discloses an amorphous carbon film whose major component is carbon and which contains silicon in an amount of 30 atomic % or less. The amorphous carbon film disclosed in the patent publication is a hard film which exhibits a high hardness, a Vickers hardness of 4,500 Hv or more, and shows good wear resistance.
However, when a hard film of good wear resistance is used for the sliding surface of various apparatuses, the hard film tends to exhibit higher aggressiveness against the mating member. Accordingly, there arises a problem that the hard film has worn off the mating member eventually.